“Is there something common about random mass killers? Something they share?”
YES, They all played violent video games. If the government is so set on banning something they should start with violent video games. There is absolutely no redeeming value to these games. They serve to desensitize people to death and killing and to teach them to shoot fast and accurate. The Columbine shooters,the Virginia Tech shooter, the Gifford shooter, the movie theater shooter, the mall shooter and yesterdays school shooter are all described as “gamers”.
Correlation does not equal causation.
Governments banning things, any things, always leads to bad results.
It's illegal to kill children. He did it anyway. He's dead.
Making more laws is feeding into the socialist, statist morass that will eventually drown you.
/johnny